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Commitd89737d

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Support "variadic" functions, which can accept a variable number of arguments
so long as all the trailing arguments are of the same (non-array) type.The function receives them as a single array argument (which is why theyhave to all be the same type).It might be useful to extend this facility to aggregates, but this patchdoesn't do that.This patch imposes a noticeable slowdown on function lookup --- a follow-onpatch will fix that by adding a redundant column to pg_proc.Pavel Stehule
1 parent2c77329 commitd89737d

38 files changed

+915
-170
lines changed

‎doc/src/sgml/catalogs.sgml‎

Lines changed: 10 additions & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -1,4 +1,4 @@
1-
<!-- $PostgreSQL: pgsql/doc/src/sgml/catalogs.sgml,v 2.168 2008/07/14 00:51:45 tgl Exp $ -->
1+
<!-- $PostgreSQL: pgsql/doc/src/sgml/catalogs.sgml,v 2.169 2008/07/16 01:30:21 tgl Exp $ -->
22
<!--
33
Documentation of the system catalogs, directed toward PostgreSQL developers
44
-->
@@ -3643,7 +3643,8 @@
36433643
<entry><literal><link linkend="catalog-pg-type"><structname>pg_type</structname></link>.oid</literal></entry>
36443644
<entry>
36453645
An array with the data types of the function arguments. This includes
3646-
only input arguments (including <literal>INOUT</literal> arguments), and thus represents
3646+
only input arguments (including <literal>INOUT</literal> and
3647+
<literal>VARIADIC</> arguments), and thus represents
36473648
the call signature of the function
36483649
</entry>
36493650
</row>
@@ -3654,8 +3655,9 @@
36543655
<entry><literal><link linkend="catalog-pg-type"><structname>pg_type</structname></link>.oid</literal></entry>
36553656
<entry>
36563657
An array with the data types of the function arguments. This includes
3657-
all arguments (including <literal>OUT</literal> and <literal>INOUT</literal> arguments); however, if all the
3658-
arguments are IN arguments, this field will be null.
3658+
all arguments (including <literal>OUT</literal> and
3659+
<literal>INOUT</literal> arguments); however, if all the
3660+
arguments are <literal>IN</literal> arguments, this field will be null.
36593661
Note that subscripting is 1-based, whereas for historical reasons
36603662
<structfield>proargtypes</> is subscripted from 0
36613663
</entry>
@@ -3669,8 +3671,10 @@
36693671
An array with the modes of the function arguments, encoded as
36703672
<literal>i</literal> for <literal>IN</> arguments,
36713673
<literal>o</literal> for <literal>OUT</> arguments,
3672-
<literal>b</literal> for <literal>INOUT</> arguments.
3673-
If all the arguments are <literal>IN</literal> arguments, this field will be null.
3674+
<literal>b</literal> for <literal>INOUT</> arguments,
3675+
<literal>v</literal> for <literal>VARIADIC</> arguments.
3676+
If all the arguments are <literal>IN</literal> arguments,
3677+
this field will be null.
36743678
Note that subscripts correspond to positions of
36753679
<structfield>proallargtypes</> not <structfield>proargtypes</>
36763680
</entry>

‎doc/src/sgml/extend.sgml‎

Lines changed: 11 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -1,4 +1,4 @@
1-
<!-- $PostgreSQL: pgsql/doc/src/sgml/extend.sgml,v 1.36 2007/08/31 21:33:48 momjian Exp $ -->
1+
<!-- $PostgreSQL: pgsql/doc/src/sgml/extend.sgml,v 1.37 2008/07/16 01:30:21 tgl Exp $ -->
22

33
<chapter id="extend">
44
<title>Extending <acronym>SQL</acronym></title>
@@ -254,6 +254,16 @@
254254
is equivalent to declaring it as <literal>f(anyenum, anyenum)</>:
255255
both actual arguments have to be the same enum type.
256256
</para>
257+
258+
<para>
259+
A variadic function (one taking a variable number of arguments, as in
260+
<xref linkend="xfunc-sql-variadic-functions">) can be
261+
polymorphic: this is accomplished by declaring its last parameter as
262+
<literal>VARIADIC</> <type>anyarray</>. For purposes of argument
263+
matching and determining the actual result type, such a function behaves
264+
the same as if you had written the appropriate number of
265+
<type>anynonarray</> parameters.
266+
</para>
257267
</sect2>
258268
</sect1>
259269

‎doc/src/sgml/plpgsql.sgml‎

Lines changed: 8 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -1,4 +1,4 @@
1-
<!-- $PostgreSQL: pgsql/doc/src/sgml/plpgsql.sgml,v 1.131 2008/06/27 01:52:59 tgl Exp $ -->
1+
<!-- $PostgreSQL: pgsql/doc/src/sgml/plpgsql.sgml,v 1.132 2008/07/16 01:30:21 tgl Exp $ -->
22

33
<chapter id="plpgsql">
44
<title><application>PL/pgSQL</application> - <acronym>SQL</acronym> Procedural Language</title>
@@ -121,6 +121,13 @@
121121
calling query, as discussed in <xref linkend="queries-tablefunctions">.
122122
</para>
123123

124+
<para>
125+
<application>PL/pgSQL</> functions can be declared to accept a variable
126+
number of arguments by using the <literal>VARIADIC</> marker. This
127+
works exactly the same way as for SQL functions, as discussed in
128+
<xref linkend="xfunc-sql-variadic-functions">.
129+
</para>
130+
124131
<para>
125132
<application>PL/pgSQL</> functions can also be declared to accept
126133
and return the polymorphic types

‎doc/src/sgml/ref/alter_function.sgml‎

Lines changed: 6 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -1,5 +1,5 @@
11
<!--
2-
$PostgreSQL: pgsql/doc/src/sgml/ref/alter_function.sgml,v 1.15 2007/09/03 18:46:29 tgl Exp $
2+
$PostgreSQL: pgsql/doc/src/sgml/ref/alter_function.sgml,v 1.16 2008/07/16 01:30:21 tgl Exp $
33
PostgreSQL documentation
44
-->
55

@@ -81,13 +81,14 @@ where <replaceable class="PARAMETER">action</replaceable> is one of:
8181

8282
<listitem>
8383
<para>
84-
The mode of an argument: either <literal>IN</>, <literal>OUT</>,
85-
or <literal>INOUT</>. If omitted, the default is <literal>IN</>.
84+
The mode of an argument: <literal>IN</>, <literal>OUT</>,
85+
<literal>INOUT</>, or <literal>VARIADIC</>.
86+
If omitted, the default is <literal>IN</>.
8687
Note that <command>ALTER FUNCTION</command> does not actually pay
8788
any attention to <literal>OUT</> arguments, since only the input
8889
arguments are needed to determine the function's identity.
89-
So it is sufficient to list the <literal>IN</> and<literal>INOUT</>
90-
arguments.
90+
So it is sufficient to list the <literal>IN</>,<literal>INOUT</>,
91+
and <literal>VARIADIC</>arguments.
9192
</para>
9293
</listitem>
9394
</varlistentry>

‎doc/src/sgml/ref/comment.sgml‎

Lines changed: 6 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -1,5 +1,5 @@
11
<!--
2-
$PostgreSQL: pgsql/doc/src/sgml/ref/comment.sgml,v 1.36 2007/08/21 21:08:47 tgl Exp $
2+
$PostgreSQL: pgsql/doc/src/sgml/ref/comment.sgml,v 1.37 2008/07/16 01:30:21 tgl Exp $
33
PostgreSQL documentation
44
-->
55

@@ -136,13 +136,14 @@ COMMENT ON
136136

137137
<listitem>
138138
<para>
139-
The mode of a function argument: either <literal>IN</>, <literal>OUT</>,
140-
or <literal>INOUT</>. If omitted, the default is <literal>IN</>.
139+
The mode of a function argument: <literal>IN</>, <literal>OUT</>,
140+
<literal>INOUT</>, or <literal>VARIADIC</>.
141+
If omitted, the default is <literal>IN</>.
141142
Note that <command>COMMENT ON FUNCTION</command> does not actually pay
142143
any attention to <literal>OUT</> arguments, since only the input
143144
arguments are needed to determine the function's identity.
144-
So it is sufficient to list the <literal>IN</> and<literal>INOUT</>
145-
arguments.
145+
So it is sufficient to list the <literal>IN</>,<literal>INOUT</>,
146+
and <literal>VARIADIC</>arguments.
146147
</para>
147148
</listitem>
148149
</varlistentry>

‎doc/src/sgml/ref/create_function.sgml‎

Lines changed: 4 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -1,5 +1,5 @@
11
<!--
2-
$PostgreSQL: pgsql/doc/src/sgml/ref/create_function.sgml,v 1.78 2007/09/11 00:06:41 tgl Exp $
2+
$PostgreSQL: pgsql/doc/src/sgml/ref/create_function.sgml,v 1.79 2008/07/16 01:30:21 tgl Exp $
33
-->
44

55
<refentry id="SQL-CREATEFUNCTION">
@@ -101,8 +101,9 @@ CREATE [ OR REPLACE ] FUNCTION
101101

102102
<listitem>
103103
<para>
104-
The mode of an argument: either <literal>IN</>, <literal>OUT</>,
105-
or <literal>INOUT</>. If omitted, the default is <literal>IN</>.
104+
The mode of an argument: <literal>IN</>, <literal>OUT</>,
105+
<literal>INOUT</>, or <literal>VARIADIC</>.
106+
If omitted, the default is <literal>IN</>.
106107
</para>
107108
</listitem>
108109
</varlistentry>

‎doc/src/sgml/ref/drop_function.sgml‎

Lines changed: 6 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -1,5 +1,5 @@
11
<!--
2-
$PostgreSQL: pgsql/doc/src/sgml/ref/drop_function.sgml,v 1.33 2007/01/31 23:26:03 momjian Exp $
2+
$PostgreSQL: pgsql/doc/src/sgml/ref/drop_function.sgml,v 1.34 2008/07/16 01:30:21 tgl Exp $
33
PostgreSQL documentation
44
-->
55

@@ -65,13 +65,14 @@ DROP FUNCTION [ IF EXISTS ] <replaceable class="parameter">name</replaceable> (
6565

6666
<listitem>
6767
<para>
68-
The mode of an argument: either <literal>IN</>, <literal>OUT</>,
69-
or <literal>INOUT</>. If omitted, the default is <literal>IN</>.
68+
The mode of an argument: <literal>IN</>, <literal>OUT</>,
69+
<literal>INOUT</>, or <literal>VARIADIC</>.
70+
If omitted, the default is <literal>IN</>.
7071
Note that <command>DROP FUNCTION</command> does not actually pay
7172
any attention to <literal>OUT</> arguments, since only the input
7273
arguments are needed to determine the function's identity.
73-
So it is sufficient to list the <literal>IN</> and<literal>INOUT</>
74-
arguments.
74+
So it is sufficient to list the <literal>IN</>,<literal>INOUT</>,
75+
and <literal>VARIADIC</>arguments.
7576
</para>
7677
</listitem>
7778
</varlistentry>

‎doc/src/sgml/typeconv.sgml‎

Lines changed: 13 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -1,4 +1,4 @@
1-
<!-- $PostgreSQL: pgsql/doc/src/sgml/typeconv.sgml,v 1.54 2008/07/11 07:02:43 petere Exp $ -->
1+
<!-- $PostgreSQL: pgsql/doc/src/sgml/typeconv.sgml,v 1.55 2008/07/16 01:30:21 tgl Exp $ -->
22

33
<chapter Id="typeconv">
44
<title>Type Conversion</title>
@@ -503,6 +503,18 @@ different argument types are considered on an equal footing regardless of
503503
search path position.
504504
</para>
505505
</step>
506+
<step performance="optional">
507+
<para>
508+
If a function is declared with a <literal>VARIADIC</> array parameter, and
509+
the call does not use the <literal>VARIADIC</> keyword, then the function
510+
is treated as if the array parameter were replaced by one or more occurrences
511+
of its element type, as needed to match the call. After such expansion the
512+
function might have effective argument types identical to some non-variadic
513+
function. In that case the function appearing earlier in the search path is
514+
used, or if the two functions are in the same schema, the non-variadic one is
515+
selected.
516+
</para>
517+
</step>
506518
</substeps>
507519
</step>
508520

‎doc/src/sgml/xfunc.sgml‎

Lines changed: 131 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -1,4 +1,4 @@
1-
<!-- $PostgreSQL: pgsql/doc/src/sgml/xfunc.sgml,v 1.130 2007/11/10 20:14:36 tgl Exp $ -->
1+
<!-- $PostgreSQL: pgsql/doc/src/sgml/xfunc.sgml,v 1.131 2008/07/16 01:30:21 tgl Exp $ -->
22

33
<sect1 id="xfunc">
44
<title>User-Defined Functions</title>
@@ -495,7 +495,7 @@ SELECT getname(new_emp());
495495
None
496496
(1 row)
497497
</screen>
498-
</para>
498+
</para>
499499

500500
<para>
501501
Still another way to use a function that returns a composite type is to
@@ -505,7 +505,7 @@ SELECT getname(new_emp());
505505
</sect2>
506506

507507
<sect2 id="xfunc-output-parameters">
508-
<title>Functions with Output Parameters</title>
508+
<title><acronym>SQL</>Functions with Output Parameters</title>
509509

510510
<indexterm>
511511
<primary>function</primary>
@@ -578,9 +578,75 @@ DROP FUNCTION sum_n_product (int, int);
578578

579579
<para>
580580
Parameters can be marked as <literal>IN</> (the default),
581-
<literal>OUT</>, or <literal>INOUT</>. An <literal>INOUT</>
581+
<literal>OUT</>, <literal>INOUT</>, or <literal>VARIADIC</>.
582+
An <literal>INOUT</>
582583
parameter serves as both an input parameter (part of the calling
583584
argument list) and an output parameter (part of the result record type).
585+
<literal>VARIADIC</> parameters are input parameters, but are treated
586+
specially as described next.
587+
</para>
588+
</sect2>
589+
590+
<sect2 id="xfunc-sql-variadic-functions">
591+
<title><acronym>SQL</> Functions with Variable Numbers of Arguments</title>
592+
593+
<indexterm>
594+
<primary>function</primary>
595+
<secondary>variadic</secondary>
596+
</indexterm>
597+
598+
<indexterm>
599+
<primary>variadic function</primary>
600+
</indexterm>
601+
602+
<para>
603+
<acronym>SQL</acronym> functions can be declared to accept
604+
variable numbers of arguments, so long as all the <quote>optional</>
605+
arguments are of the same data type. The optional arguments will be
606+
passed to the function as an array. The function is declared by
607+
marking the last parameter as <literal>VARIADIC</>; this parameter
608+
must be declared as being of an array type. For example:
609+
610+
<screen>
611+
CREATE FUNCTION mleast(VARIADIC numeric[]) RETURNS numeric AS $$
612+
SELECT min($1[i]) FROM generate_subscripts($1, 1) g(i);
613+
$$ LANGUAGE SQL;
614+
615+
SELECT mleast(10, -1, 5, 4.4);
616+
mleast
617+
--------
618+
-1
619+
(1 row)
620+
</screen>
621+
622+
Effectively, all the actual arguments at or beyond the
623+
<literal>VARIADIC</> position are gathered up into a one-dimensional
624+
array, as if you had written
625+
626+
<screen>
627+
SELECT mleast(ARRAY[10, -1, 5, 4.4]); -- doesn't work
628+
</screen>
629+
630+
You can't actually write that, though &mdash; or at least, it will
631+
not match this function definition. A parameter marked
632+
<literal>VARIADIC</> matches one or more occurrences of its element
633+
type, not of its own type.
634+
</para>
635+
636+
<para>
637+
Sometimes it is useful to be able to pass an already-constructed array
638+
to a variadic function; this is particularly handy when one variadic
639+
function wants to pass on its array parameter to another one. You can
640+
do that by specifying <literal>VARIADIC</> in the call:
641+
642+
<screen>
643+
SELECT mleast(VARIADIC ARRAY[10, -1, 5, 4.4]);
644+
</screen>
645+
646+
This prevents expansion of the function's variadic parameter into its
647+
element type, thereby allowing the array argument value to match
648+
normally. <literal>VARIADIC</> can only be attached to the last
649+
actual argument of a function call.
584650
</para>
585651
</sect2>
586652

@@ -795,13 +861,45 @@ DETAIL: A function returning a polymorphic type must have at least one polymorp
795861
For example:
796862
<screen>
797863
CREATE FUNCTION dup (f1 anyelement, OUT f2 anyelement, OUT f3 anyarray)
798-
AS 'select $1, array[$1,$1]' LANGUAGEsql;
864+
AS 'select $1, array[$1,$1]' LANGUAGESQL;
799865

800866
SELECT * FROM dup(22);
801867
f2 | f3
802868
----+---------
803869
22 | {22,22}
804870
(1 row)
871+
</screen>
872+
</para>
873+
874+
<para>
875+
Polymorphism can also be used with variadic functions.
876+
For example:
877+
<screen>
878+
CREATE FUNCTION anyleast (VARIADIC anyarray) RETURNS anyelement AS $$
879+
SELECT min($1[i]) FROM generate_subscripts($1, 1) g(i);
880+
$$ LANGUAGE SQL;
881+
882+
SELECT anyleast(10, -1, 5, 4);
883+
anyleast
884+
----------
885+
-1
886+
(1 row)
887+
888+
SELECT anyleast('abc'::text, 'def');
889+
anyleast
890+
----------
891+
abc
892+
(1 row)
893+
894+
CREATE FUNCTION concat(text, VARIADIC anyarray) RETURNS text AS $$
895+
SELECT array_to_string($2, $1);
896+
$$ LANGUAGE SQL;
897+
898+
SELECT concat('|', 1, 4, 2);
899+
concat
900+
--------
901+
1|4|2
902+
(1 row)
805903
</screen>
806904
</para>
807905
</sect2>
@@ -852,6 +950,16 @@ CREATE FUNCTION test(smallint, double precision) RETURNS ...
852950
avoid the problem by not choosing conflicting names.
853951
</para>
854952

953+
<para>
954+
Another possible conflict is between variadic and non-variadic functions.
955+
For instance, it is possible to create both <literal>foo(numeric)</> and
956+
<literal>foo(VARIADIC numeric[])</>. In this case it is unclear which one
957+
should be matched to a call providing a single numeric argument, such as
958+
<literal>foo(10.1)</>. The rule is that the function appearing
959+
earlier in the search path is used, or if the two functions are in the
960+
same schema, the non-variadic one is preferred.
961+
</para>
962+
855963
<para>
856964
When overloading C-language functions, there is an additional
857965
constraint: The C name of each function in the family of
@@ -2952,7 +3060,25 @@ CREATE FUNCTION make_array(anyelement) RETURNS anyarray
29523060
LANGUAGE C IMMUTABLE;
29533061
</programlisting>
29543062
</para>
3063+
3064+
<para>
3065+
There is a variant of polymorphism that is only available to C-language
3066+
functions: they can be declared to take parameters of type
3067+
<literal>"any"</>. (Note that this type name must be double-quoted,
3068+
since it's also a SQL reserved word.) This works like
3069+
<type>anyelement</> except that it does not constrain different
3070+
<literal>"any"</> arguments to be the same type, nor do they help
3071+
determine the function's result type. A C-language function can also
3072+
declare its final parameter to be <literal>VARIADIC "any"</>. This will
3073+
match one or more actual arguments of any type (not necessarily the same
3074+
type). These arguments will <emphasis>not</> be gathered into an array
3075+
as happens with normal variadic functions; they will just be passed to
3076+
the function separately. The <function>PG_NARGS()</> macro and the
3077+
methods described above must be used to determine the number of actual
3078+
arguments and their types when using this feature.
3079+
</para>
29553080
</sect2>
3081+
29563082
<sect2>
29573083
<title>Shared Memory and LWLocks</title>
29583084

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